In recent years, thermal transfer systems have been developed to obtain prints from pictures which have been generated electronically from a color video camera. According to one way of obtaining such prints, an electronic picture is first subjected to color separation by color filters. The respective color-separated images are then converted into electrical signals. These signals are then operated on to produce cyan, magenta and yellow electrical signals. These signals are then transmitted to a thermal printer. To obtain the print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. The two are then inserted between a thermal printing head and a platen roller. A line-type thermal printing head is used to apply heat from the back of the dye-donor sheet. The thermal printing head has many heating elements and is heated up sequentially in response to one of a cyan, magenta or yellow signal. The process is then repeated for the other two colors. A color hard copy is thus obtained which corresponds to the original picture viewed on a screen. Further details of this process and an apparatus for carrying it out are contained in U.S. Pat. No. 4,621,271, the disclosure of which is hereby incorporated by reference.
Dye receiving elements for thermal dye transfer generally comprise a transparent or reflective support having on one side thereof a dye image-receiving layer and on the other side thereof a backing layer. Writing on such a backing layer with pencils, ball point pens, solvent pens, rolling ball pens, and fountain pens is desirable, especially in the case of thermal dye transfer prints used in a postcard format. Pens, such as rolling ball and fountain pens, use aqueous inks of permanent and non-permanent (water-soluble) types. A backing layer for thermal dye transfer receivers that accepts and retains not only pencil and oily inks, but also water-based inks, is therefore desirable. Water-soluble inks are subject to running or smearing if contacted by moisture after drying. Such smearing of writing would be undesirable.